Protestors set fire on a police vehicle on Election Day in Phnom Penh. Photo: Xinhua

Cambodia’s opposition party said on Monday it would challenge the results of a general election in which it made impressive gains even though the ruling party of Prime Minister Hun Sen retained power.

His Cambodian People’s Party claimed victory in Sunday’s polls though its 90-seat majority in the National Assembly shrunk to 68 seats. Provisional results showed the opposition Cambodia National Rescue Party took the remaining 55 seats, a major boost from the combined opposition total of 29 in the last parliament.

The results were a slap in the face for Hun Sen’s government, but the CNRP said on Monday it would push matters further. It said in a statement that voting was marked by huge irregularities, and it demanded a joint investigation committee be established, comprising representatives from the two parties, the National Election Committee, the United Nations and local and international NGOs.

“The Cambodia National Rescue Party will not accept the election results that we have heard because there are many irregularities that occurred during the election,” party leader Sam Rainsy said.

Whatever its merits, the CNRP challenge would appear to be mostly bluster. Hun Sen’s ruling party has control or dominating influence over all the state bureaucracy and the courts and will almost certainly affirm the CPP victory. Past appeals have not succeeded, and it was unclear what the opposition would do if its complaints were not sustained.

Foreign countries such as the United States, which had expressed doubts before the election about its fairness, are unlikely to pursue the point with enthusiasm. They have accepted the results of past elections with much more open intimidation and violence as fair enough, and will likely regard this year’s results as a major step forward.

Critics alleged that the election process was heavily rigged. Rainsy’s party and nonpartisan groups charged that the ruling party used the machinery of government and security forces in an unfair manner to reward or pressure voters.

They also said that voter registration procedures were badly flawed, possibly leaving more than one million people disenfranchised — the point on which the CNRP is challenging the results. The independent Committee for Free and Fair Elections said on Saturday that the ink with which voters were supposed to stain their fingers to prevent them from voting twice was not indelible as claimed.

The actual extent of voting irregularities was not clear, despite many anecdotal accounts spread on social media such as Twitter.

Hun Sen’s party and the government-appointed National Election Committee said the election process was fair.

If the results stand, it would give the much beleaguered opposition a strong platform for future growth. However, a simple majority is sufficient for most legislative business, ensuring that the CPP can continue to administer the country much as it wishes, though with increased sensitivity to public opinion. The CPP has an overwhelming majority of local administration posts as well.

Hun Sen has been in power for 28 years and says he has no intention of stepping down soon. His authoritarian rule has given him a stranglehold over the state bureaucracy that makes challenges to his authority difficult to mount.

The general election was Cambodia’s fifth since 1993, when the United Nations helped stage the country’s first free polls since the 1975-79 genocidal rule of the Khmer Rouge and a subsequent period of civil war and one-party rule.

A pressing question is how Hun Sen will react to events. Mercurial in temperament, historically he has accepted neither defeat nor victory with good grace.

After his party ran second in 1993, Hun Sen insisted on being named co-prime minister, then ousted his partner in government four years later in a bloody coup. After election victories in later years, he showed a pattern of cracking down on critics.

Hun Sen, 60, has a reputation as a tough and wily survivor, starting with his defection from the Khmer Rouge to Vietnam, which after invading to oust the radical regime installed him first as foreign minister and later as prime minister.

Rainsy, 64, has long been the thorn in Hun Sen’s side. He spent the Khmer Rouge years in France, where he was educated in economics and political science. As a member of a royalist party, he served as finance minister in the government elected in 1993, but was kicked out from his party and his post for his outspoken anti-corruption stand.

Rainsy founded his own party in 1995, and two years later he narrowly escaped being killed in a grenade attack on a rally he was leading. The perpetrators were never brought to justice but were suspected of being linked to Hun Sen’s bodyguards.

Despite his party’s good showing on Sunday, Rainsy will be in an uncertain state. He was not allowed to run as a candidate or even vote in the election, because he missed the registration deadlines as he stayed abroad for almost four years to avoid a jail term for convictions that he said were politically motivated. He returned July 19 only after receiving a royal pardon at the behest of Hun Sen, his longtime and bitter rival.

The pardon was an evident effort by Hun Sen to appease critics of the election process, including the United States, who suggested that Rainsy’s exclusion was a major sign that the polls would not be free and fair.

The CNRP showed its combative stance on Sunday night, even as it was aware of its gains.

Rainsy had issued a statement early on Sunday evening claiming victory, but later retracted it.

Rainsy’s wife, Tioulong Saumura, a candidate in Phnom Penh, said she did not accept the ruling party’s figures. Asked if she thought the CNRP won more than 55 seats, she replied: “Of course. Almost everywhere we lead. No way we have 55 and they have 68.”